From: Anshuman Khandual <khandual@xxxxxxxxxxxxxxxxxx> Subject: mm: hugetlb: soft-offline: dissolve source hugepage after successful migration Currently hugepage migrated by soft-offline (i.e. due to correctable memory errors) is contained as a hugepage, which means many non-error pages in it are unreusable, i.e. wasted. This patch solves this issue by dissolving source hugepages into buddy. As done in previous patch, PageHWPoison is set only on a head page of the error hugepage. Then in dissoliving we move the PageHWPoison flag to the raw error page so that all healthy subpages return back to buddy. [arnd@xxxxxxxx: fix warnings: replace some macros with inline functions] Link: http://lkml.kernel.org/r/20170609102544.2947326-1-arnd@xxxxxxxx Link: http://lkml.kernel.org/r/1496305019-5493-5-git-send-email-n-horiguchi@xxxxxxxxxxxxx Signed-off-by: Anshuman Khandual <khandual@xxxxxxxxxxxxxxxxxx> Signed-off-by: Naoya Horiguchi <n-horiguchi@xxxxxxxxxxxxx> Signed-off-by: Arnd Bergmann <arnd@xxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- include/linux/hugetlb.h | 31 +++++++++++++++++++++++++++---- mm/hugetlb.c | 10 +++++++++- mm/memory-failure.c | 5 +---- mm/migrate.c | 2 ++ 4 files changed, 39 insertions(+), 9 deletions(-) diff -puN include/linux/hugetlb.h~mm-hugetlb-soft-offline-dissolve-source-hugepage-after-successful-migration include/linux/hugetlb.h --- a/include/linux/hugetlb.h~mm-hugetlb-soft-offline-dissolve-source-hugepage-after-successful-migration +++ a/include/linux/hugetlb.h @@ -472,6 +472,7 @@ static inline pgoff_t basepage_index(str return __basepage_index(page); } +extern int dissolve_free_huge_page(struct page *page); extern int dissolve_free_huge_pages(unsigned long start_pfn, unsigned long end_pfn); static inline bool hugepage_migration_supported(struct hstate *h) @@ -550,15 +551,37 @@ static inline unsigned int pages_per_hug { return 1; } -#define hstate_index_to_shift(index) 0 -#define hstate_index(h) 0 + +static inline unsigned hstate_index_to_shift(unsigned index) +{ + return 0; +} + +static inline int hstate_index(struct hstate *h) +{ + return 0; +} static inline pgoff_t basepage_index(struct page *page) { return page->index; } -#define dissolve_free_huge_pages(s, e) 0 -#define hugepage_migration_supported(h) false + +static inline int dissolve_free_huge_page(struct page *page) +{ + return 0; +} + +static inline int dissolve_free_huge_pages(unsigned long start_pfn, + unsigned long end_pfn) +{ + return 0; +} + +static inline bool hugepage_migration_supported(struct hstate *h) +{ + return false; +} static inline spinlock_t *huge_pte_lockptr(struct hstate *h, struct mm_struct *mm, pte_t *pte) diff -puN mm/hugetlb.c~mm-hugetlb-soft-offline-dissolve-source-hugepage-after-successful-migration mm/hugetlb.c --- a/mm/hugetlb.c~mm-hugetlb-soft-offline-dissolve-source-hugepage-after-successful-migration +++ a/mm/hugetlb.c @@ -1459,7 +1459,7 @@ static int free_pool_huge_page(struct hs * number of free hugepages would be reduced below the number of reserved * hugepages. */ -static int dissolve_free_huge_page(struct page *page) +int dissolve_free_huge_page(struct page *page) { int rc = 0; @@ -1472,6 +1472,14 @@ static int dissolve_free_huge_page(struc rc = -EBUSY; goto out; } + /* + * Move PageHWPoison flag from head page to the raw error page, + * which makes any subpages rather than the error page reusable. + */ + if (PageHWPoison(head) && page != head) { + SetPageHWPoison(page); + ClearPageHWPoison(head); + } list_del(&head->lru); h->free_huge_pages--; h->free_huge_pages_node[nid]--; diff -puN mm/memory-failure.c~mm-hugetlb-soft-offline-dissolve-source-hugepage-after-successful-migration mm/memory-failure.c --- a/mm/memory-failure.c~mm-hugetlb-soft-offline-dissolve-source-hugepage-after-successful-migration +++ a/mm/memory-failure.c @@ -1575,11 +1575,8 @@ static int soft_offline_huge_page(struct if (ret > 0) ret = -EIO; } else { - /* overcommit hugetlb page will be freed to buddy */ - SetPageHWPoison(page); if (PageHuge(page)) - dequeue_hwpoisoned_huge_page(hpage); - num_poisoned_pages_inc(); + dissolve_free_huge_page(page); } return ret; } diff -puN mm/migrate.c~mm-hugetlb-soft-offline-dissolve-source-hugepage-after-successful-migration mm/migrate.c --- a/mm/migrate.c~mm-hugetlb-soft-offline-dissolve-source-hugepage-after-successful-migration +++ a/mm/migrate.c @@ -1252,6 +1252,8 @@ put_anon: out: if (rc != -EAGAIN) putback_active_hugepage(hpage); + if (reason == MR_MEMORY_FAILURE && !test_set_page_hwpoison(hpage)) + num_poisoned_pages_inc(); /* * If migration was not successful and there's a freeing callback, use _ -- To unsubscribe from this list: send the line "unsubscribe mm-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
